An air foil thrust bearing does not support a thrust of a rotary body by using an oil film like a ball bearing or a roller bearing. An air foil thrust bearing supports a thrust of a rotary body by supplying high-pressure air between an air foil and the rotary body and forming an air film.
The air foil thrust bearing is mainly used for a high-speed rotary body corresponding to 100,000 RPM or more, such as a compressor or a blower. However, manufacturing costs thereof are high and quality stability deteriorates due to a complex manufacturing process thereof.
As illustrated in FIG. 1, in an air foil thrust bearing, bump foils 80 are disposed on an upper surface of a base plate 60 and a top foil 90 is disposed on upper surfaces of the bump foils 80.
The top foil 90 may have an inclined portion 99 and a flat portion 92. The number of the bump foils 80 may be plural.
If a bearing disk 20 is rotated as a rotor 10 rotates, a pressure is formed between the top foil 90 and the bearing disk 20 to support a load as air is introduced along the inclined portion 99 of the top foil 90.
An edge portion 94 of the top foil 90 may be attached to a base plate 60 through welding. Edge portions 84 of the bump foils 80 may be attached to the base plate 60 through welding.
In the conventional air foil thrust bearing, after the bump foils 80 are attached to the base plate 60 through welding, the top foil 90 is attached to the base plate 60 through welding.
In this way, individual jigs are used to weld the bump foils 80 and the top foil 90. However, because the bump foils 80 and the top foil 90 are formed of very small and thin sheet metals, the locations of the bump foils 80 and the top foil 90 are distorted so that an assembly process thereof is very troublesome and defects frequently occur.
Further, when the bump foils 80 and the top foil 90 are welded at inaccurate locations, the performance of the air foil thrust bearing deteriorates. Also, the bump foils or the top foil may separate when a welding defect occurs so that the rotor 10 may be damaged.